Complete Grapheme & Phonetic Inventory

1. Historical & Archaeological Genesis

The Inscriptional Medium & Material Culture

The evolution of the Old Uyghur script from its Sogdian precursor represents a masterclass in adaptive paleography ^[1]. Unlike the stone-bound runiform traditions of the Orkhon, the Uyghur script favored the flexibility of the reed pen and brush on paper and parchment ^[2]. This transition to a cursive, vertical medium dictated a radical shift in stroke order: the script was written downwards, with ligatures forming the connective tissue of the administrative state ^[4]. The fluidity of the brush allowed for the 'cursive compression' observed in silk-road documents, where the physical constraints of the paper roll influenced the height-to-width ratio of the glyphs ^[10].

2. Phonological Architecture & Grapheme Mapping

Articulatory Mechanics & Acoustic Distinctions

The Old Uyghur system required mapping the Turkic vowel harmony—a complex system of front/back and rounded/unrounded vowels—onto a script originally designed for the Indo-European Sogdian ^[1], ^[5]. By repurposing the Yodh (𐱉) and Waw (𐱅) as primary vocalic indicators, the Uyghur scribes achieved a feat of phonological engineering that allowed for precise morphological distinction ^[8].

Vowel Dynamics: Inherent Sounds & Diacritic Modulations

Unlike the abugidas of India, the Uyghur script utilized a system of 'materia lectionis' where specific consonants doubled as vowels ^[5]. This allowed for a compact syllabic packaging, critical for the rapid administrative record-keeping required by the Uyghur Khaganate ^[8].

3. Mathematical & Geometric Symmetries

Grid Geometry, Stroke-Count Economy & Symmetry Rules

The script functions on a modular grid system where the vertical axis is defined by the baseline of the reed pen stroke ^[12]. The economy of stroke-count is mathematically optimized to minimize the 'lift' of the brush, characterized by the formula:
$$S = \sum_{i=1}^{n} (l_i \cdot c_i)$$
where $l$ represents the length of the stroke and $c$ the curvature coefficient. This geometric efficiency allowed for high-density information storage, essential for the extensive economic records found in the Turfan oasis ^[6].

4. Epigraphic Inscriptions, Corpus Examples & Transcriptions

Authentic Epigraphic Passages & Scribal Corpus

Original Inscription: 𐱎𐱃𐱈𐱀𐱂
Paleographic Transliteration: s-d-t-a-g
Phonetic Realization: /sadaq/
Interlinear Gloss: [sadaq] (quiver)
English Translation: A quiver (symbol of military readiness).

Original Inscription: 𐱊𐱅𐱇
Paleographic Transliteration: k-u-x
Phonetic Realization: /kux/
Interlinear Gloss: [kux] (grief/sorrow)
English Translation: Grief, as reflected in the Manichaean liturgical texts ^[15].

5. Comparative Epigraphic Evolution Matrix

6. Decipherment Milestones & Modern Linguistic Legacy

Ancient Scribal Logic in Contemporary Linguistics

The decipherment of the Uyghur corpus was facilitated by the discovery of bilingual Manichaean texts ^[11], ^[15]. These fragments served as the Rosetta Stones of the Silk Road, allowing linguists to map the cursive ligatures back to their phonemic origins ^[9]. Today, the computational analysis of these vertical scripts informs modern HTR (Handwritten Text Recognition) models, proving that the ancient administrative logic remains a cornerstone of algorithmic linguistics ^[9], ^[13].

Academic References & Epigraphic Sources

1. SIMS-WILLIAMS, N., KORKMAZ, F., KESKİN, B. (2017). THE SOGDIAN SOUND-SYSTEM AND THE ORIGINS OF THE UYGHUR SCRIPT. Istanbul University Faculty of Letters Journal of Turkish Language and Literature. DOI: https://doi.org/10.26561/iutded.369178
2. Morano, E. (2018). Some Sodicological Remarks on the Sorpus of the Berlin Turfan Manichaean Sogdian Manuscripts in Manichaean Script: among Books, Glossaries, Letters, Booklets, Bilingual and Trilingual Texts, Normal, Bold and Cursive Script. Written Monuments of the Orient. DOI: https://doi.org/10.17816/wmo35154
3. Vajda, S. (n.d.). Cursive Bengali Script Recognition for Indian Postal Automation. Agence Bibliographique de l'Enseignement Supérieur. DOI: https://doi.org/10.70675/5c3fca10z833az4175z8cefzb3da3849ff58
4. Iskhakov, M., Goyibov, B. (2026). Graphemological Features of The Sogdian “Ancient Letters” Script. International Journal Of History And Political Sciences. DOI: https://doi.org/10.37547/ijhps/volume06issue03-14
5. AYAZLI, Ö. (2020). Soğdca Bazı Sözcüklerin Eski Uygurcadaki İmlası. International Journal of Old Uyghur Studies. DOI: https://doi.org/10.46614/ijous.743040
6. Begmatov, A. (2021). Two Sogdian Toponyms in Arabic and Chinese Sources, and their Attestation as Commodity Terms in Sogdian and Uyghur Economical Documents. DABIR. DOI: https://doi.org/10.1163/29497833-00801002
7. Yueqing, Z. (2026). Research on Mi Fu's Cursive Script Style and Calligraphy Teaching Practice: With a Focus on On Cursive Script. Research on Literary and Art Development. DOI: https://doi.org/10.47297/wsprolaadwsp2634-786550.20260703
8. Scholarly Research Council (n.d.). Old Uyghur Script. Encyclopedia of Turkic Languages and Linguistics Online. DOI: https://doi.org/10.1163/2667-3029_etlo_sim_032216
9. Griffiths, R. (2024). Handwritten Text Recognition (HTR) for Tibetan Manuscripts in Cursive Script. Verlag der Österreichischen Akademie der Wissenschaften. DOI: https://doi.org/10.1553/tibschol_erc_htr
10. Hagen, F. (2025). Hieratic. Cambridge University Press. DOI: https://doi.org/10.1017/9781009673600
11. Chunakova, O., Dragoni, F., Morano, E. (2017). A forgotten Manichaean Sogdian bifolio in Sogdian script. Written Monuments of the Orient. DOI: https://doi.org/10.17816/wmo35122
12. Humera Rafique, Javid, T. (n.d.). An Insight for Cursive Context-Specific Printed Script Recognition. Open Engineering Inc. DOI: https://doi.org/10.31224/osf.io/z6jkn
13. Naeini, S., Khademi, M., Nikookar, A., Bani, Z. (2012). A Feature-based Approach to Segmentation of Online Persian Cursive Script. International Journal of Modeling and Optimization. DOI: https://doi.org/10.7763/ijmo.2012.v2.149
14. Kozintcev, M. (2020). Turkic Poetic Passages Written in Uyghur Vertical Script from the Collection of the Institute of Oriental Manuscripts, RAS. Письменные памятники Востока. DOI: https://doi.org/10.17816/wmo46591
15. Morano, E. (2024). Where the Demons Fell. A Manichaean Sogdian Manuscript in Sogdian Script from Mani’s Book of the Giants. Journal of Iranian Linguistics. DOI: https://doi.org/10.46991/jil/2024.01.01
16. Farrell, T. (2026). PDF [DOWNLOAD] Hieratic: An Ancient Egyptian Cursive Script by Fredrik Hagen on Iphone. ResearchHub Technologies, Inc.. DOI: https://doi.org/10.55277/researchhub.mzprknyu.1
17. Ahmed, S., Razzak, M., Yusof, R. (2020). Foundations of Cursive Scene Text. Cursive Script Text Recognition in Natural Scene Images. DOI: https://doi.org/10.1007/978-981-15-1297-1_1
18. LINDSAY, W. (1913). IRISH CURSIVE SCRIPT.. Zeitschrift für celtische Philologie. DOI: https://doi.org/10.1515/zcph.1913.9.1.301
19. Ahmed, S., Razzak, M., Yusof, R. (2020). Progress in Cursive Wild Text Recognition. Cursive Script Text Recognition in Natural Scene Images. DOI: https://doi.org/10.1007/978-981-15-1297-1_5
20. Scholarly Research Council (n.d.). Figure 2: Top row: original Arabic script (unlabeled). Bottom row: Arabic script with labels marking the upper baseline, baseline, and down line of the Arabic cursive writing.. PeerJ. DOI: https://doi.org/10.7717/peerjcs.1465/fig-2